Compensating impression roller mount for stencil duplicator

ABSTRACT

A stencil duplicating machine including two independently pivotably impression roll mounting brackets which are adjustably biased to vary the contact pressure between the impression roll and the duplicator drum. The impression roll shaft is mounted with a clearance fit in the brackets so as to allow limited radial movement of the shaft with respect to the bracket to provide uniform contact pressure between the roller and the drum and to compensate for any misalignment. The shaft is also spring biased between the brackets so as to be easily removable.

10l/l32.5 197/33 W 1451 Sept. 17, 1974 2,936,706 5/1960 Springer et a1. MOUNT O IL DUPLlCATOR 3,229,798 1/1966 Grashoff.......................... 3,652,083 3/1972 Bosshardt...... Inventor: Edward Sp g ag 111 3,712,214 1/1973 Kaneko ct 73 He r1nc.,Ch' 111. 1 ye lcdgo Primary Examiner-Robert E. Pulfrey 1971 Assistant Examiner-R. E. Suter Attorney, Agent, or Firm-Davis, McCaleb & Lucas [57] ABSTRACT 101/116 523 A stencil duplicating machine including two indepen- 01/232 234 H 6 dently pivotably impression roll mounting brackets 101/132 132 5 which are adjustably biased to vary the contact pressure between the impression roll and the duplicator R f n d drum. The impression roll shaft is mounted with a e ere ces l e clearance fit in the brackets so as to allow limited ra- UNITED STATES PATENTS dial movement of the shaft with respect to the bracket to provide uniform contact pressure between the rol- Assignee:

[22] Filed:

United States Patent Springer 4] COMPENSATING IMPRESSION ROLLER 21 Appl. No.: 186,956

[58] Field of Search ler and the drum and to compensate for any misalignment. The shaft is also spring biased between the 0 101/247 brackets so as to be eas1ly removable.

197/33 9 Claims, 30 Drawing Figures XX 2 23 33 22 OU/l 1 11 W00 11 1,698,187 l/l929 Clatworthy 2,185,682 l/l940 Pittman........... 2,622,518 12/1952 Peterson et a1. 2,778,299 l/l957 PARENTEDSEP 1 mm 3 .aas.172

SHEET "on or 1 INVENTOR Edward M. Springer PATENIED 3.835.772-

'snm 0SOF13 UVVENTOP Edward M. Springer PATENTED SEPI 71974 SHEET [17 0F 13 INVENTOR Edward M. Springer A TTORNEVS PATENIEDSEPITIBH 3.835.772

SHEET oanr13' INVENTOP Edward M. Springer B V D9 Rfuwa, 5 281002 i lljwzavz ATTORNEYS lllllll INVENT'OR Edward M. Springer BV v 0 Xucu, 57 61004 /fillyhzcz2z ATTORNEYS PAIENIEDSEPI w 3.835.772

sum 130F13' INVENTOP Edward M. Springer BV p m, 32am, 59mm ffl zagmm ATTORNEYS COMPENSATING IMPRESSION ROLLER MOUNT FOR STENCIL DUPLICATOR BACKGROUND OF THE INVENTION The field of the invention is generally that of ink-type duplicating machines in which ink is transferred from the interior of a drum, through an ink pad and a stencil carried by the drum, onto copy sheets.

In such machines the copy sheets are fed, one at a time, from a stack, through a bight between the drum and an impression roll which presses the sheet against the stencil as it is drawn through the bight. The impression roll must not be pressed against the ink-covered stencil or it will smear the stencil and transfer ink to the backs of succeeding sheets. Mechanism must therefore be provided for preventing contact between the impression roll and the stencil when no sheet is fed to the drum. Providing such mechanism is complicated be: cause the presence of a relatively fragile copy sheet must be sensed to trigger the very substantial forces required for moving the impression roll to press the copy sheet against the stencil. A further complication is that modern duplicating machines must produce more than 100 copies per minute, so there is very little time for the impression roll to be moved after sensing the presence or absence of a sheet.

Machines of the type with which the present invention is concerned feed sheets in two separate movements with a definite stop or pause between them. There is an initial movement of the sheet from the stack, followed by a final movement across the drum. It is important that this initial movement be stopped at a definite point and at a definite time correlated with the rotation of the drum, to properly register the printing on the sheet. Prior machines have not precisely controlled such stopping and starting of the sheets resulting in a loss of precision in the printed copy.

A problem, sometimes called dotting develops in conventional duplicating machines at high speeds, resulting for all practical purposes in an upper speed limit which will not produce acceptable copy. Conventional duplicating machine drums have a cylindrical peripheral wall with perforations through which the ink flows to a pad, and thence to the stencil. At high speeds, ink flows more readily to the stencil portions over the perforations than to the portions between, giving an uneven or dotted pattern to the printing.

Stencils vary in their ability to transmit ink, so it is necessary to provide some mechanism for adjusting the pressure between the impression roll and drum during printing.

The duplicating machines are relatively complicated, having many parts which must be kept clean and in good operating order by regular maintenance procedures. For this purpose it is important that the drum be easily removable to provide access to parts beneath it.

Stencils commonly have a backing sheet which acts as a cushion during typing, and provides convenient means for handling as when assembling the stencil on a drum. After the stencil is so assembled, the backing sheet is removed. Some stencils have a perforated line near the head portion along which the backing sheet may be torn off. Others, such as certain electronic stencils, do not have such a perforated line and the operator has to tear the backing sheet along a ruler or other separate straight edge tool held against the drum. This is not completely satisfactory because the operator must hold the tool by one hand, aligned by eye, and the resulting torn edge is often crooked.

SUMMARY OF THE INVENTION A principal object of the present invention is to provide an ink-type duplicating machine which functions with precision at high speeds and can be manufactured in volume at a reasonable cost.

Another object is to provide such a duplicating machine having improved mechanism for stopping a sheet with precision between initial feeding and final printing movements, to obtain highly precise registration of printed copy.

Another object is to provide an auxiliary, cylindrical ink supply between the periphery of the drum and the ink pad and stencil to eliminate the dotting problem described above.

Another object is to provide improved mechanism for regulating the pressure between the impression roll and the drum.

Another object is to provide mechanism controlled by a single manually operable knob or shaft for releasing the drum from the machine.

Another object is to provide a drum with a stencil clamp having a built-in knife edge for removing the backing sheets from certain types of stencils.

Another object is to provide flexible strip strippers for positively guiding a copy sheet into and out of printing engagement with the drum, and mechanism for holding such strips out of wearing engagement with a stencil on the drum.

Another object is to provide improved feed tension control mechanism by which the weight of feed wheels on a stack of copy sheets is variable to effectively feed sheets of different thicknesses.

Another object is to provide a duplicating machine in which an ink pad and stencil can be replaced, and an entire drum can be exchanged, as for instance during multi-color printing, quickly and easily, without soiling the hands of the operator.

A specific object is to provide mechanism for moving the impression roll including a flexible actuated frame spring-biased toward the drum and including a pair of pivoted brackets supporting the impression roll, a single cam rotatable with the drum, and a rigid actuating frame operable by the single cam to pivot both brackets simultaneously in a direction to move the impression roll away from the drum against the bias of the springs.

Another specific object is to provide a novel antifriction roller arrangement and rigid actuating frame between a single cam and a pair of brackets independently supporting the ends of the impression roll.

Other objects and advantages will be apparent from the following description taken in connection with the drawings in which:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a machine illustrating the present invention, the figure showing side ornamental plates or covers which enclose certain operative parts of the mechanism;

FIG. 2 is a partial plan view of the machine shown in FIG. 1;

FIG. 3 is a partial vertical section taken on line 3-3 of FIG. 2;

FIG. 4 is an enlargement of a portion of FIG. 3;

FIG. 4A is an external fragmentary view of the drum as seen in the direction of arrows 4A4A in FIG. 4;

FIG. 5 is a side elevation of the driving and timing mechanism viewed along line 5-5 of FIG. 2, but with the respective ornamental cover removed;

FIG. 6 is an enlargement of a portion of FIG. 5;

FIG. 7 is a perspective view of the printing drum and some associated parts removed from the machine;

FIG. 8 is an enlarged fragmentary cross-sectional view of FIG. 7 taken along the line 8-8;

FIG. 9 is an enlarged fragmentary longitudinal crosssectional view taken along line 9-9 of FIG. 2 showing mechanism operated by a single shaft and knob for connecting and disconnecting the drum in the machine;

FIG. 10 is a sectional elevational view taken generally along line 1010 of FIG. 2, with certain parts removed showing the relationship of certain components as a copy sheet is fed forward to begin the printing cycle;

FIGS. 11-16 are schematic views similar to FIG. 10 but on a reduced scale showing subsequent operative positions of components as the copy sheet is advanced through the machine;

FIG. 17 is a perspective view of certain parts of the mechanism;

FIG. 18 is an enlarged fragmentary view of FIG. 17 along line 18-18;

FIG. 19 is a fragmentary view of FIG. 5 with the side frame removed to show one of the brackets which supports the impression roll and showing three adjusted positions of the spring biasing means;

FIG. 20 is an enlarged sectional view of FIG. 19 taken along line 20-20;

FIG. 21 is a view similar to FIG. 20 showing the impression roll partially disconnected;

FIG. 22 is a fragmentary view of FIG. 5 showing the mechanism for supporting and moving one of the forwarding rollers, with the bight between the rollers being shown in open condition;

FIG. 23 is a fragmentary view similar to FIG. 22 but showing the bight between the rollers closed;

FIG. 24 is a plan view partly in section of the mechanism shown in FIGS. 22 and 23;

FIG. 25 is an enlarged view of a portion of FIG. 24;

FIG. 26 is a perspective view showing the drum connected to a removable carrying bail for transfer to a storage stand;

FIG. 27 is a view of the bail and drum supported on a storage stand remote from the duplicating machine;

FIG. 28 is a fragmentary perspective view of the drum supported on the storage stand; and

FIG. 29 is a fragmentary view of FIG. 28 showing the details of the shoulder and rib arrangement for supporting the drum.

DESCRIPTION OF THE PREFERRED EMBODIMENT The machine shown in the drawings comprises a housing 30 having a pair of side plates or frames 32 and 34; a feed table or tray 36 for supporting a stack 63 of copy sheets 64 in position to be advanced into the housing; feed means 38 for advancing sheets from the stack; a pair of relatively movable forwarding rollers 40 and 42 defining a first, variable bight 358 therebetween; a rotatable drum 44; an impression roll 46 movable relative to the drum and defining with the drum a second, variable bight 360; and guide means including lower and upper guide plates 362 and 364 and strippers 375 for guiding copy sheets along a path of movement from the tray through the first and second bights. Paper stop means 54 and paper sensing means 56 are disposed along the path of movement between the first and second bights.

Referring now in more detail to the above mentioned components and their cooperation in the machine, the side plates 32 and 34 are held in fixed spaced relationship by a number of rigid cross members bolted or otherwise fastened therebetween. These include transverse struts 58 and 60, rod 62, and other elements forming part of the housing.

The feed table 36 is shown and described in detail in Springer U.S. Pat. No. 3,417,988 issued Dec. 24, 1968 on Sheet Guiding Mechanism. Briefly, it supports a stack 63 of copy sheets 64 at the input end in position to be advanced one at a time into the housing. The operation is automatic, the rate of feed being one sheet per each rotational cycle of the drum. At the output end of the machine is a receiving tray 66 to collect the printed sheets.

Feed means 38 comprises a pair of rubberlike feed wheels 68 slidable to different spacings along a shaft 70 for sheets of different widths. The ends of the shaft 70 are rotatably joumaled in a pair of arms 72 which are pivoted for up and down swinging movement outside the respective side plates 32 and 34, about the aligned axes of two separate shafts 74. The arms 72 have upwardly offset sections 76 held by bolts 78 to the ends of a spacer rod 80. An arcuate slot 81 in each side plate provides clearance for the shaft 70 and rod during up and down movements of the feed wheels 68.

As shown in FIG. 5, the end of shaft 70 adjacent the side plate 32 is connected through an overrunning clutch 82 to an outer race 86 having external gear teeth 88. An inner race 84 is fixed to shaft 70, and sprags (not shown) between the inner and outer races drive shaft 70 counterclockwise when the outer race rotates counterclockwise as seen in FIG. 5. The sprags overrun or free wheel when the outer race rotates clockwise.

The outer race 86 is rotatably driven by a train of gears 90 and 92 carried by the respective arm 72. Gear 90 is rotatable on shaft 94 which is mounted on arm 72 intermediate its ends. Gear 92 is rotatable on shaft 74. Both gears 90 and 92 are held in place by snap rings 96. Thus, it will be seen that the train of gears for driving feed wheels 68 swing vertically with pivotal movement of shaft 74, allowing the feed wheels to move down as the stack of sheets on the feed table is used up during operation of the machine.

The upper and lower forwarding rollers 40 and 42 have a series of rollers 98 and 102 on shafts and 104 respectively.

The ends of shaft 100 are rotatably joumaled in side plates 32 and 34. Externally of side plate 32, as shown in FIG. 5, shaft 100 is connected to an inner race 106 of an overrunning clutch 108. The outer race 110 has external gear teeth meshed with both gear 92 and gear sector 112. Sprags (not shown) between the inner and outer races enable the shaft 100 to be rotated by the outer race only in a counterclockwise direction as seen in FIG. 5. Clutch 108 overruns when its outer race rotates clockwise.

At the other end of shaft 100, exteriorly of side plate 34, there is a friction brake generally designated 114 (FIGS. 17 and 18). This comprises a flexible friction strap 116 having a riveted loop 118 anchored to a stub shaft 120 on the exterior of side plate 34. Strap 116 has a bend 122 tensioned about a flat cylindrical groove 124 at the end of shaft 100 by a spring 126 held by pin 128 on side plate 34. This holds the shaft 100 braked against rotation unless the shaft is positively driven by a torque sufficient to override the friction of strap 116 against the brake groove 124.

As best shown in FIGS. .22-25, the ends of lower forwarding roller shaft 104 are loosely rotatably journaled in bearings 128 carried by levers 130. The levers 130, together with the shaft 104, comprise a flexible actuated frame for supporting the annular roller elements 102. The loose journal connection represented by the clearance between each bearing 128 and shaft extension 129 (FIG. 25) comprises in effect a limitedly swivelable connection enabling the ends of the shaft 104 to move up and down independently of one another, within limits, thereby enabling the ends of the lower forwarding roller assembly 42 to press uniformly against the upper forwarding roller assembly 40.

Each lever 130 has an integral boss'131 at its midsection pivoted for rocking movement about a reduced end portion 133 of an actuating shaft 132. Each end portion of shaft 132 is rotatably journaled in a bushing 134 in one of the side plates 32 and 34. The shaft 132 comprises part of a rigid actuating frame including actuating levers 136 which are held by screws 138 to T- handle 139 fast to the reduced diameter extension 133. A washer 141 is provided between members 131 and 139.

Each lever 136 has an inwardly extending transverse pin 140 engageable edgewise with the end portion of the corresponding lever 130 opposite the end portion carrying the shaft 104.

A tension spring 142 is connected between pin 140 and an anchor pin 144 on side plate 32. This biases the rigid actuating frame (shaft 132 and levers 136) counterclockwise as viewed in FIGS. 22 and 23.

Two springs 146, both external of side plates 32 and 34, are connected between an anchor opening 148 in each lever 130 and an anchor pin 150 on side plate 32 or 34. Springs 146 exert a torque on the flexible actuating frame (shaft 104 and levers 130) urging the movable lower forwarding roller assembly 42 upward against the fixed upper forwarding roller assembly 40. Both the actuating and actuated frames referred to are thus biased counterclockwise (FIGS. 22 and 23) about the same shaft, namely shaft 132.

At the end of shaft 132 exteriorly of side plate 32 (FIG. 24) lever 136 has an opposite extension arm 152 with a follower roller 154 engageable with a cam for automatic operation to be described.

There is a lost motion relationship between levers 130 and 136 on both sides of the housing. This effectively enables the lower forwarding roller assembly 42 to be moved downward as a unit, but allows the ends of roller assembly 42 to seek their own positions when moved upwardly for the best, uniform engagement with roller assembly 40. This lost motion arrangement is best shown in FIG. 23. There, shaft 132 and lever 136 are rotated counterclockwise sufficiently to disengage pin 140 from the lower edge 156 of actuated arm 130. This, of course, would be true on both sides of the machine. Because the shaft 104 and levers comprise a limitedly flexible frame, each spring 146 moves each corresponding lever 130 in a direction to close the first bight 358, between the rollers 40 and 42, on each side of the machine as shown in FIGS. 3 and 23. When the integral actuator arm 152 and lever 136 are rocked clockwise about the axis of shaft 132, both pins will engage the under edges 156 of arms 130, rotating the latter clockwise (FIGS. 22 and 23) about shaft 132 and opening the bight between rollers 40 and 42. This opened bight is shown in FIG. 22.

Returning now to the description of the synchronized drive mechanism for the feed wheels 68 and forwarding rollers 40 and 42, the drum 44 is driven by a motor 158. The drum, in turn, then drives the feed wheels and forwarding rollers.

As shown in FIGS. 7, 8 and 9, drum 44 comprises a pair of circular ends or heads 160 and a partially cylindrical peripheral wall 162 having apertures 164. An open mesh screen 166 covers the wall portion 162 and, as will be described, provides an auxiliary, cylindrical ink reservoir immediately beneath an ink pad 168 for instant access of ink thereto. Such auxiliary ink reservoir receives ink through the apertures 164 from a main ink reservoir 170 within the drum.

The apertured cylindrical wall section 162 shown in FIGS. 7 and 8 is the printing portion of the drum which supports the ink pad 168 and a stencil 547. Between the leading edge 172 and the trailing edge 174 (FIG. 10) of the cylindrical printing segment 162, there is a recess 176 defined by an ink retaining wall 178 having a threaded cap 180 through which ink is put in the main reservoir 170. The recess 176 also contains ink pad clamp means 182 and stencil clamp means 184 both of which will be described in detail.

Each drum end or head 160 has a generally rectangular reinforcing plate 186 (FIGS. 7, 8 and 9) affixed thereto as by soldering or brazing. Plates 186 are parallel and each has an outer, eccentric lug 188 and a pair of circumferentially spaced lugs 190 disposed closer to the rotational axis of the drum. As will be described, there is a lug 188 at each end of the drum. These provide convenient temporary anchor points for a carrying bail, to move the drum back and forth between the machine and a separate storage stand. The two pairs of lugs 190 at opposite end of the drum 44 provide means for transmitting torque between the drum 44 and supporting members 218 and 236, and they enable initial, positive alignment of the drum 44 and supporting members 218 and 236 along their common rotational axis before they are connected together, and thereby make it possible to rapidly connect and disconnect the drum within the machine. To avoid inadvertent reversal of the drum within the machine, the opposite pairs of lugs 190 may be located at different radial distances from the center.

Referring to FIG- 9, an axial sleeve or tube 192 is soldered or brazed between the ends 160 of the drum. Within the sleeve is an axially shiftable shaft 194 and an internally threaded bushing 196 which is fixed in position by soldering or brazing to the interior surface of sleeve or tube 192. The shaft has an inner extension 198 of sufficiently reduced diameter to clear the threaded bore of bushing 196. A guide washer 200 is supported on the extension 198 and is slidable within the bore of sleeve 192. A coil spring 202 is compressed between an internal snap ring 204 in a groove at one end of the sleeve 192, and an external snap ring 206 in a groove on shaft 194. The spring biases the shaft 194 to the right (FIG. 9), toward a position wholly contained between the ends of the sleeve 192.

The mechanism for supporting the drum 44 between the side plates 32 and 34 will now be described.

A supporting and driving tube 208 is rotatably journaled within a sleeve bearing 210 in side wall 34. A drive pulley 212 is fastened to the supporting tube 208 in any suitable manner as for example by the set screw 214. A flanged hub 216 is fastened to the end of supporting tube 208 interiorly of the side plate 34, by solder or a press fit. A disc-like supporting member 218 is fastened to the hub 216. An alignment and driving member 200 is fastened as by rivets 222 to the inside surface of supporting member 218. As best shown in FIG. 9, the member 220 is T-shaped, having radially outwardly facing ledges or shoulders 226 for supporting the lugs 190 to axially align the drum sleeve 192 with the supporting tube 208. Lugs 190 are spaced sufficiently to straddle the rib or stem portion 224 of the T-shaped member 220 and thereby provide an effective rotatable driving connection between the supporting disc member 218 and the drum.

A second supporting and driving tube 228 (comprising a substantial counterpart of supporting tube 208) is rotatably joumaled within a sleeve bearing 230 fixed within side plate 32. A center shaft 232 is rotatable with supporting tube 228 and has an end bore 233 positioned to receive the outer end portion 264 of shaft 194 when extended as shown in FIG. 9.

A flanged hub 234 (similar to 216) is fastened to the inner end of center shaft 232 and is rotatable with that shaft and with supporting tube 228 in normal operation. A disc-like supporting member 236, which may be identical with member 218, is connected to the flanged hub 234 and rotatable therewith. A T-shaped locking member 220 and lugs 190, as described above for the other end of the drum, provide a releasable, rotatable driving connection between the supporting disc member 236 and the drum. A cam 238 is fastened to and rotatable with the sleeve 228. Cam 238 moves the impression roll 46 relative to the drum by mechanism which will be described.

By a worm and pinion means not forming part of the present invention, and therefore not shown, the tube 228 and 232 are rotatably adjustable to vary the cam 238 relative to the drum. This raises or lowers the printing on the copy sheets in response to rotation of adjusting discs 239 on wheel 241 (FIG. 1).

Externally of the side plate 32 a drive bushing 240 is fastened to the supporting tube 228 by a set screw 242. Fastened to the drive bushing 240 and rotatable therewith is a drive gear 244 and cams 246 and 248. As will be described, cam 246 moves the paper stop means 54, and cam 248 (fastened to 246 by spacer rivets 250) moves forwarding roller 42.

As shown in FIG. 3, the power source for the machine is the motor 158. This is connected through a suitable speed reducing power transmission (not shown) to drive pulley 212 shown in FIG. 9. Optionally, for a more simplified, less automatic version of the machine, one of the tubes 208 and 228 may be turned by a hand operable crank not shown.

Thus, rotation of tube 208 by the drive pulley 212 (or the optional crank) rotates supporting drive disc member 218. This rotates the drum and the other supporting drive disc member 236 through the two sets of T- shaped locking members 220 and lugs 190. Disc 236 drives tube 228 and the parts rotatable therewith including drive gear 244 and cams 246 and 248.

Having described the parts for supporting the drum, the means operated by a single handle for quickly connecting and disconnecting the drum between the sideframes will now be described.

Refer again to FIG. 9. A shaft 252 having a reduced diameter outer extension 254 is rotatable, and axially slidable, within supporting tube 208. A knob or handle 256 is held by a set screw 258. A snap ring 260 in an internal groove in tube 208 retains the shaft 252.

At its extreme inner end, shaft 252 has an externally threaded reduced diameter extension 262, adapted to be screwed into bushing 196 as shown in solid lines in FIG. 9.

To disconnect the drum, the knob 256 need only be rotated sufficiently to disconnect threaded extension 262 from threaded bushing 196. Then, by drawing the handle 256 outwardly from the tube 208 until the outer shoulder of shaft 252 engages the snap ring 260, the threaded inner end portion 262 will be moved to the broken line position shown in FIG. 9, disconnecting the right end of the drum at hub 216. As the shaft end 262 moves away from the extension 198 of shaft 194, the latter will shift automatically to the right (FIG. 9) until its outer end 264 is recessed within the end of the drum as shown in broken lines. This releases the left end of the drum at hub 234. Then, with the drum rotated so the locking members 220 are upward, the drum can be lifted straight upward, free of the machine.

Conversely, the drum 44 (or another drum with different colored ink) may be assembled quickly by lowering the drum into position for engagement of the lugs with the locking members 220, followed by pressing the shaft 252 inward and turning handle 256 to engage the screw threads in members 196 and 262.

When the shaft 194 is completely retracted by the spring 202 into the drum, the reduced diameter inner end 198 is positioned slightly to the right of the threaded bushing 196. This is shown in broken lines in FIG. 9. This permits initial inward movement of the shaft 252 to engage the end 198 of shaft 194 and shift the opposite end 264 into bore 233 in shaft 232 before the threads in members 262 and 196 are engaged. The assembly can then be moved to the solid line locked position shown in FIG. 9 by only one or two subsequent turns of the knob 256.

By the foregoing, the drive from motor 158 to the drive gear 244 has been described. The driving connections from gear 244 to the sector 112 will now be described to complete the driving train for the machine.

Drive gear 244 rotates crank gear 266 about pin 268 fastened to side plate 32. Crank pin 270 is connected by lever 272 to the midpoint of lever 274 which rocks back and forth about pin 276 fastened to side plate 32. Lever 274 is held to pin 276 by snap ring 278. At the free end of lever 274 a pin 280 is engaged with an arcuate slot 282 in sector 112. The sector is rockable about a pin 284 fastened to side plate 32 and a snap ring 286 holds it in place.

The sector has an arcuate line of gear teeth 288 meshed with gear teeth 290 on the outer race 110 of overrunning clutch 108 which has previously been described.

Cyclic rotation of feed wheels 68 and forwarding roller 40 may now be summarized as follows. Rotation of crank gear 266 causes crank lever 272 to rock lever 274 back and forth. This alternately rocks gear sector teeth 288 clockwise, and counterclockwise, about shaft 284. Because of the overrunning clutches 82 and 108, previously described, counterclockwise movement (FIG. of sector 112 rotatably drives the feed wheels 68 in a counterclockwise direction to feed the top sheet 64 from the stack on the feed table 36; at this time, the clutch 108 is overrunning and therefore not driving the forwarding rollers. Next, when sector 112 rocks in a clockwise direction, overrunning clutch 108 drives the upper forwarding roller in a counterclockwise direction to further advance the sheet toward the drum. These separate advancing movements of the sheet by the feed wheels and forwarding rollers are synchronized with operation of the other parts of the mechanism as will be described.

As shown in FIGS. 17 and 19, the impression roll 46 is carried by a shaft 292 havinjg its opposite ends respectively journaled in brackets 294, 294 which are independently pivotable about stub shafts 296 extending inwardly from side plates 32 and 34. The detailed construction of the mounting enabling the ends of the shaft 292 to be rotatably journaled in the brackets 294, yet sufficiently pivotal to enable the brackets to move up and down independently, is best shown in FIGS. 17, 19, 20 and 21 and will be described subsequently.

Each bracket 294 has an elongated body portion 320 and an out-tumed flanged portion 322. The body portion has a pivot opening 324 engaging pivot shaft 296, and a catch pin 326 on the outer side of the bracket at the end remote from pivot shaft 296. Each bracket has interrupted elongated slot means consisting of a pair of horizontal, aligned slots 328 and 330, the latter having three detent notches 332, 334, and 336 in the upper edge.

An adjustment member 338 is manually movable lengthwise along each bracket to vary the pressure of the impression roll against the drum. Each adjustment member includes an elongated body portion 340 and an inturned grip portion 342 and each has a pair of pins 344 and 346 engageable respectively within the slots 328 and 330. The pins have enlarged heads 348 to keep them within the slots.

A tension spring 350 is connected between pin 344 and an anchor pin 352 on the adjacent side plate 32 or 34. Similarly a tension spring 354 is connected between pin 346 and an anchor pin 356 on each side plate. As shown in FIGS. 17 and 19, the lines of action of springs 350 and 354 extend substantially parallel to the vertical planes of movement of the brackets 294. Further, the lines of action of these springs are transverse to the lines of adjustment movement of the adjustment members 338.

In the embodiment disclosed, the adjustment members 338 are movable to three different torque positions to select three degrees of pressure of the impression roll against the drum. When pins 346 are in notches 336, the lines of action of the springs 350 and 354 will be at a maximum distance from the pivot pin 296, and the combined upward pull of the springs to exert torque to the brackets and press the impression roll toward the drum will be at the maximum. When pins 346 are in middle notches 334, as shown in solid lines in FIG. 19, the lines of action of the springs will be somewhat closer to the pivot shaft 296, and the torque on the brackets and the upward pressure of the impression roll against the drum will be at an intermediate value. When pins 346 are in notches 332, the line of action of spring 354 will be on the opposite side of pivot shaft 296 (see FIG. 19) so that only springs 350 will exert any effective torque and upward pressure on the impression roll. Thus, each adjustment member 338 is movable between a maximum torque position An important feature of the machine is the mechanism enabling the impression roll 46 to be connected quickly and easily into the machine, or to be disconnected therefrom. This is best shown in FIGS. l7, 19, 20 and 21.

The impression roll comprises a resilient cylindrical cover 351 concentrically mounted on shaft 292. The ends of shaft 292 have reduced diameter extensions 353 and 355. A snap ring retainer or stop 357 is provided in a groove at the end of each extension. Sleeve bearing members 359 and 361, which may be identical, and each having an external flange 363, are slidably mounted on extensions 353 and 355, respectively. A coil spring 365 on extension 353 is seated between a shoulder 367 and the flange of bearing member 359, biasing the latter in an outward direction. At the other end of shaft 292, a rotatable washer 369 is interposed between shoulder 371 and the flange of bearing member 361.

In operating position, the impression roll 46 is assembled with bearings 359 and 361 seated within openings 373 in the brackets 294 as shown in FIG. 20.

To disconnect the impression roll 46 from the machine, the operator simply grasps the roll and presses it in a direction to compress spring 365 thereby withdrawing bearing 361 from opening 373, as shown in FIG. 21. So released, the impression roll may simply be pivoted about its remaining engaged end and swung out of the machine. The snap ring retainers 357 function as stops to limit outward movement or loss of the bearing members when the impression roll is removed from the machine.

As described, it is important that the brackets 294 be free to pivot independently, to the extent that opposite ends of the impression roll will be pressed uniformly against the drum. The ends of the shaft 292 must, of course, rotate within the bearings 359 and 361 and the bearings must allow for limited pivotal movement of the ends of the shaft relative to the brackets. This is provided simply and practically in the present invention by making the clearances between the bearings and the shaft, and between the bearings and the brackets large enough to allow such combined rotational and pivotal movement.

As shown in FIG. 3, guide mechanism is provided for guiding copy sheets 64 successively along a path of movement from the stack 63 on the feed table 36 to the first bight 358 (between the forwarding rollers) and then to the second bight 360 (between the impression roll and the drum). This guide mechanism includes lower and upper supporting and guide plates 362 and 364. The guide plates extend between the side plates 32 and 34 and have transverse flanges fastened thereto by bolts 366 and 368.

The lower supporting and guide plate 362 includes a vertical wall 370 with studs 372 for engaging the feed table 36, an upwardly inclined wall 374, and a lower horizontal wall 376 extending along and below the path of movement of the sheets. The upper supporting and guide plate 364 includes a downwardly inclined wall 378 and an upper horizontal wall 380 extending along and above the path of movement of the sheets. Horizontal wall portions 376 and 380 have openings 382 and 384 for the individual follower roller elements 102 and 98 respectively.

The paper stop means generally designated 54 comprises a transversely extending plate having an upwardly inclined portion 386 terminating in vertical fingers 388 which extend through openings in the lower horizontal guide wall 376 when in their fully raised position (FIG. The stop plate is fastened as by screws 390 to rock shaft 392 which is pivoted between the side plates 32 and 34.

As best shown in FIG. 5, a paper stop actuating lever 394 is connected to rock shaft 392 externally of the side plate 32. The upper end of lever 394 has a follower roller 396 engageable with cam 246 already described in connection with FIG. 9. The lower end of lever 394 is connected by a spring 398 to an anchor pin 400 on side plate 32 and biases the lever 394 in a clockwise direction to keep follower 396 engaged with the cam 246.

Another important part of the invention is springtype paper stripper means functioning as an extension of the upper supporting and guide plate 364. This feature is best shown in FIGS. 2 and 3.

As shown in FIG. 2, the axial length of the drum 44 exceeds that of the impression roll 46. A pair of transversely spaced, flexible strips 375 of material such as spring steel are fastened by bolts 377 to the top of the inclined wall 378. The strips 375 extend in an outward direction over the end of the upper horizontal guide wall 380, tangent to the bottom of the drum as shown in FIG. 3, to anchor pins 379 on the side frames. Thus, the stripper strips 375 will positively guide a sheet to the drum and then positively strip it from the bottom of the drum as it passes beyond the second bight by reason of the fact that the strips 375 extend continuously from the end of horizontal guide wall 380 to a position well beyond the second bight 360.

Each axial end portion of the drum has a peripheral ring 381 providing a slightlyy raised circumferential surface engaging the strips 375 and keeping them out of wearing engagement with a stencil on the drum.

An important feature of the strips 375 is that because they are mounted on top of and substantially upstream of the edge of horizontal guide wall 380, they continuously engage the edges of a copy sheet to, through, and beyond the second bight. This guides the sheet to the drum, and positively strips it from the drum after printing.

Mechanism will now be described for moving the impression roll 46 toward and away from the drum and for holding the impression roll out of contact with the drum when the machine operates without paper passing through it.

A rigid actuating frame, generally U-shaped and designated 399 (FIG. 17) is interposed between the single cam 238, (previously described in connection with FIG. 9) and the two independently movable brackets 294. The rigid actuating frame consists of a countershaft 401 pivotally joumaled in side plates 32 and 34, and a pair of actuating arms 402 which extend toward the brackets 294. Each arm 402 has a lower roller 404 engageable with the top edge 406 of a corresponding bracket. One of the arms 402 has a follower roller 408 engagable with cam 238 previously described in connection with FIG. 9. A tension spring 410 (FIGS. 3 and 17) hold the rollers 404 engaged with bracket edges 406. This promotes quiet operation.

Because the actuating frame 399 is rigid, downward movement of either arm 402 is accompanied by identical movement of the other arm. Thus, in spite of the fact that both brackets 294 are independently movable to promote uniform upward pressure of the impression roll against the drum, both ends of the impression roll will be moved simultaneously downwardly from the drum when the high portion H of cam 238 engages follower roller 408.

The part of the mechanism which holds the impression roll 46 out of contact with the drum in the absence of a copy sheet will now be described. A latch shaft 412 is pivotally journaled between the side plates 32 and 34. A pair of identical catch levers 414 are mounted at the ends of the latch shaft. Paper sensing means 56 comprise radial fingers 416 carried by latch shaft 412 intermediate its ends.

The paper stop fingers 388 and the paper sensing fingers 416 are both along the path of movement of the copy sheets between the first and second bights as shown in FIG. 3.

The latch shaft 412 is pivotable between a latching position and an unlatching position. In the latching position shown in FIGS. 10 and 17, the catch levers are swung to a substantially vertical position with their notches 420 engaging bracket catch pins 326 to hold the brackets 294 in position to keep impression roll 46 out of contact with the drum. In the unlatching position, shown for example in FIGS. 14, 15 and 16, the catch levers 414 are swung free and enable the springurged brackets to move the impression roll upward and press a copy sheet against a stencil on the drum.

Ornamental covers 422 and 424 (FIG. 1) are provided to cover the mechanism above described which is on the external surfaces of the side plates 32 and 34.

A hand wheel 241 is connected with supporting tube 228 (by means not shown) and adjusting wheels 239 may be rotated in one direction or the other and (by means not shown) may rotate shaft 232 relative to supporting tube 228 to advance or retard the cam 238 rela tive to the supporting disc 236. This is no part of the present invention so will not be described in detail, but, briefly, this adjustment raises or lowers the location of printing on the copy sheet, as previously described.

An important part of the invention, facilitating the uniform distribution of ink over the copy sheet at high speeds is the open mesh screen 166 (FIG. 8) which is stretched permanently about the apertured, cylindrical peripheral wall portion 162 and comprises an integral part of the drum. This communicates via apertures 164 with the main interior ink reservior inside the drum. As the drum rotates ink is distributed over the inside of the wall 162 and passes through the apertures 164 into the interstices of the open mesh screen 166 

1. In a duplicating machine having a housing; feed means for advancing sheets from a stack into said housing; a pair of forwarding rollers defining a first bight therebetween; a drum supported for rotation within said housing; an impression roll movable relative to said drum and defining a second bight therebetween; and guide means effective to guide said sheets along a path of movement from said stack through said first and second bights; the improvement comprising: a. a pair of elongated brackets independently pivotably movable in spaced parallel planes about a common axis; b. said brackets having means for supporting the respective opposite ends of the impression roll for rotation about an axis which is tiltable in a direction radially of the drum axis by independent pivotable movement of said brackets while supporting the impression roll; c. an elongated adjustment member mounted on each of said brackets, spring means connected between each adjustment member and said housing urging the respective ends of said impression roll toward said drum; d. on said elongated adjustment members being mounted for movement along a line of adjustment extending lengthwise of the corresponding bracket to vary the distance of each said spring means from said common axis and thereby change the biasing effect of said spring means on said bracket; e. a pivotable latch shaft having a pair of catch levers at opposite ends and having radial paper sensing means intermediate said opposite ends of said latch shaft, said latch shaft being pivotable to a latching position in which said paper sensing means intersect said path of movement when no sheet is advanced and said catch levers are engageable with said brackets to hold said impression roll spaced from said drum; f. a rigid actuating frame including a pivotable countershaft having a pair of actuating arms respectively engageable with said brackets; g. a cam rotatable with said drum and engageable with one of said actuating arms to simultaneously move both of said brackets and the impression roll connected thereto away from said drum; and h. means for advancing a sheet along said path of movement to a position just short of said paper sensing means and for simultaneously rotating said cam to a position to disengage said brackets from said catch levers and place said latch shaft in freely pivotable condition, means for continuing advance of said sheet to displace said paper sensing means while said cam continues to hold said brackets disengaged from said catch levers to pivot said latch shaft from said latching position while in such freely pivotable condition.
 2. A duplicating machine according to claim 1 in which: each adjustment member is slidably mounted on the corresponding bracket; each said spring means comprises a pair of springs for applying a force against the corresponding adjustment member along lines of action substantially parallel to said spaced parallel planes in which said brackets are movable, and having tHeir lines of action extending transversely to said line of adjustment movement of the corresponding adjustment member; and detent means is provided between each adjustment member and the corresponding bracket effective to hold said adjustment member in a predetermined position on the bracket.
 3. A duplicating machine according to claim 2 in which: each adjustment member has a pair of transverse pins at opposite lengthwise end portions thereof slidably mounted within longitudinal slot means in the corresponding bracket; and said detent means comprises notches along said slot means in each of said brackets which receive a corresponding one of said pins in selected positions of adjustment.
 4. A duplicating machine according to claim 1 in which: said impression roll is mounted concentrically on a shaft having opposite end portions extending from said ends of said impression roll; said opposite end portions of said shaft have bearing members within which said shaft is rotatable; one end portion of said shaft being axially movable within one of said bearing members and having a spring urging said one bearing member outward against one of said brackets; and said brackets having aligned seats which receive the respective bearing members therein; whereby said impression roll may readily be assembled between said seats or disassembled therefrom by an initial endwise movement of said impression roll toward one of said seats in a direction to compress said spring to thereby shorten the spacing between said bearing members and release said shaft from the opposite seat.
 5. In a duplicating machine having a housing, a drum supported for rotation within said housing, an impression roll rotatable about an axis and movable relative to said drum and effective to press a copy sheet against said drum, means for adjusting the pressure of said impression roll against said copy sheet on said drum including: a pair of brackets spaced apart and at the respective ends of the drum, said brackets being independently pivotable in spaced parallel planes about pivot shaft means on a common axis which is parallel to the axis of said impression roll; said impression roll having its opposite ends respectively rotatably supported in said brackets by means enabling pivotal movement of the axis of said impression roll relative to each bracket at all rotated positions of said impression roll for independent movement of each of said opposite ends toward said drum; an adjustment member carried by each said bracket and movable thereon along a line of adjustment extending lengthwise of the bracket; a pair of springs connected to each adjustment member at points spaced apart along said line of adjustment; each said pair of springs applying force against the corresponding adjustment member along lines of action substantially parallel to said spaced parallel planes in which said brackets are movable, and having their lines of action extending transversely of said line of adjustment of the corresponding adjustment member and having their other ends connected to said housing; whereby movement of each adjusting member along its said line of adjustment varies the combined torque exerted by the corresponding pair of springs on the corresponding bracket about said common axis to thereby vary the pressure of said impression roll against said copy sheet on said drum.
 6. In a duplicating machine according to claim 5, the line of action of one spring on each bracket being adjustable to a position in which it will substantially intersect said common axis to minimize the torque effect of said one spring in one adjusted position of said adjustment member.
 7. In a duplicating machine according to claim 5, each adjustment member being movable between a maximum torque position and a minimum torque position, the corresponding pair of springs having their lines of action spaced from the axis in said maximum torque position, and having their said lines oF action on opposite sides of said common axis in said minimum torque position.
 8. In a duplicating machine according to claim 7, detent means acting between each adjustment member and bracket for holding said adjustment member selectively in said maximum and minimum torque positions.
 9. In a duplicating machine according to claim 8, additional detent means acting between each adjustment member and bracket for holding each said adjustment member selectively in at least one intermediate position between said maximum and minimum torque positions. 